[triumph thrust washer]

[1976 TR6]

1976 Triumph TR6

[triumph alloy thrust washer]

Improved solid alloy thrust washer
Above shown in various stages of manufacturing

A Serious Antidote for the Thrust Washer Blues

The Triumph TR2, TR3, TR4, TR4A, TR5, TR250, TR6, Spitfire, Vitesse, GT6, and Herald are highly sought after collectable classic British cars that were manufactured by Standard Triumph and British Leyland Motor Company during the 1950's through the late 1970's. To this day, they provide their owners with driving enjoyment to the nth degree. But as with any mechanical gizmo that includes hundreds of moving parts, there are a few quirks that need to be dealt with.

In this case, the quirk has to do with the original thin plated steel engine crankshaft thrust washer that Triumph installed in their engines. This small and often neglected piece of metal plays a big role in keeping all of the internal engine parts lined up, and has long been known to be a weakness of these otherwise long-lived, smooth running engines.

From the time these cars initially rolled off the production line, the rear crankshaft thrust washer was generally expected to last up to around 50,000 miles, depending upon driving habits of the operator. Since the front crankshaft thrust washer would not be subjected to much load, its life expectancy is expected to be much longer.

Since mostly all Triumphs included a manual transmission that utilized a very strong clutch spring, the little rear thrust washer was destined to wear due to the terrific force applied to it whenever the driver would press the clutch pedal to the floor to shift gears.

Many of these cars have changed hands over the years, and most new owners don't think about this little known maintenance issue that involves regular crankshaft end float measurements to determine whether the thrust washer has worn to its limits.

Unfortunately, many owners have discovered this problem only after learning that the friction and wear caused by the crankshaft flange surface spinning against the thrust washer mating surface, has worn through the very thin nickel-copper plating [exposing the undesirable bare steel surface] without warning. Now that the thrust washer has lost all of its desirable bearing surface, the two opposing steel surfaces begin to wear against one another very rapidly, causing damage to the crankshaft surface.

While the thrust washer continues to wear thin, it falls out of its nesting place, and drops to the bottom of the oil pan. The driver unknowingly continues driving the car without any clue of what is going on inside the engine, and the crankshaft continues grinding its way into the side of the bearing end cap. By the time the owner realizes there is something wrong - due to an audible sound - extensive engine block damage has already occurred.

[triumph OEM thrust washer]

Pictured above is the original "OEM" style thrust washer installed at the factory.
The thin alloy plating wore through to solid steel and caused rapid wear.

As a result of my very own experience that matches the story above, I decided to come up with a solution to replace the original Triumph OEM thrust washer. I consulted with a good friend named Dr. Shengli Liu. Dr. Liu holds a PHD from the University of Wisconsin (Madison, WI) in the study of Metallurgy (study of metals) & Tribology (study of friction and wear). With Dr. Liu's assistance, we selected the most desirable, modern solid alloy material for this application, and designed a new thrust washer to replace the outdated version. The new version is very similar to the original design geometry, but has an increased bearing surface area for improved contact with the crankshaft bearing mating surface.

The new solid alloy thrust washer has superior friction and wear properties, and excels in areas where lubrication can sometimes be limited. As with any thrust washer, whether it is solid alloy or the outdated plated steel, regular crankshaft end-float inspections need to be a part of regular maintenance for these cars. When the end float measurement indicates the need, the owner simply replaces the old thrust washer with a new solid alloy thrust washer.

In addition to the Triumph models listed above, this thrust washer also fits certain models of TVR and Mazda Miata.

e-mail to Scott Helms


More about the thrust washer blues

Many thanks for helping to keep the British car hobby thriving.

Scott Helms - sportycars@britishcarweek.org

The long version of the story.....

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